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Poutrina et al. developed an analytical approach allowing to relate a particular geometry of a metamaterial unit cell incorporating nonlinear elements to the effective nonlinear susceptibilities characterizing the resulting effective medium. The approach allows the prediction, analysis, and possible enhancement of the nonlinear response of a metacrystal, exploiting and proving a long-predicted concept of the increased nonlinear response in metamaterial structures. The theory shows an excellent...

In a paper published in Applied Physics Letters, Larouche et al. present the first quantitative characterization of nonlinear metamaterials. Using an approach based on transfer matrices previously developed in the CMIP, they determine the quadratic nonlinear magnetic susceptibility of a slab of varactor-loaded split ring resonators to be 3.5 m/V. This gigantic value confirms qualitative predictions found in the literature and supports the validity of an analytical model developed by Poutrina et...

The acoustic "sisters" of electromagnetic invisibility cloaks are long-sought devices that could defeat sonars. The existence of two types of acoustic waves in elastic media, however, makes acoustic cloaking very hard to achieve. The paper by Yaroslav Urzhumov and co-workers, published recently in the New Journal of Physics (July 12, 2010), is the first report on the feasibility of building an acoustically undetectable elastic cloak.
Acoustic cloaking transformations from attainable material...

The MMI coupler is a key component in optical integrated circuits. Its main function is to combine or split optical signals, enabling the development of powerful multiplexing devices and integrated sensors. In a paper published in Optics Express (September 28, 2009 issue), Yu-Ju Tsai and co-workers investigate metallic MMI couplers that support long-range surface plasmons instead of conventional electromagnetic waves. Although the use of metals introduces material losses in the system, the...

Transformation optics can be used to design media with unique properties for the manipulation of electromagnetic waves. The transformation optical approach can be used not only to control the path of light, but also to change the way that currents and charges (or sources) behave when they interact with light. The interaction of electromagnetic waves is fundamental in the design of antennas. In the latest issue of Applied Physics Letters, Jeffery Allen and colleagues demonstrate several...

ECE Professor David Smith led a successful proposal team to secure $6.25M for a five year MURI titled Transformational Optical Metamaterials that aims to design optical media that can achieve functionality not obtainable by conventional optics. Smith plans to explore applications such as electromagnetic cloaking, sub-diffraction limited imaging and improved solar cell efficiency through omni-directional light concentrators. Collaborators include Duke’s Steve Cummer and Nan Jokerst, as well as...

Dan Roberts was awarded a Fannie and John Hertz Foundation Fellowship for postgraduate study in the physical sciences. The Hertz Fellowship is merit based and widely considered to be one of the most prestigious graduate fellowships awarded. The fellowship provides approximately $250,000 of support over a five year tenure. One of the goals is to provide financial independence for fellows, allowing them to pursue innovative research as per their own interests. Dan will defer his fellowship for...

There has been a large amount of interest generated by recent work on invisibility cloaking. While the concept of invisibility has many corollaries in popular fiction which inspire the imagination, from the Harry Potter stories to Predator, researchers are taking only the first steps- both theoretical and experimental- towards these sci-fi goals. The general approach being used, which combines transformation optics with metamaterials operating in the microwave region of the electromagnetic...

Transformation optics is a new tool for the design of electromagnetic media. Using transformation optics, researchers can visualize the interaction of certain complex materials with light as a warping of space. The physical basis underlying this connection, however, extends also to sources of light—electric currents, for example. In a recent paper published in Optics Express, Nathan Kundtz and colleagues illustrate the application of transformation optics to electric currents. In one example,...